Former Gov. Mark Sanford was abandoned this week by the National Republican Congressional Committee, which confirmed via a spokeswoman that it will not spend any money on his behalf in the 1st District special election in South Carolina.

Now deep-pocketed outside grounds say they have no plans to boost Sanford over his opponent, Democrat Elizabeth Colbert Busch, in the May 7 contest.

The last straw came Tuesday evening, when The Associated Press reported Sanford’s ex-wife accused him of trespassing on her property earlier this year. The revelation came as a big surprise to national Republicans, who were already wavering on his candidacy.

The GOP’s calculation boils down to this: With a 17-seat majority, they can afford to lose this race because they will probably pick it up again in 2014. Besides, they see greater risk in supporting Sanford — especially if he embarrasses the party on a national stage. Again.

“Mark’s behavior is inexplicable,” said a South Carolina operative and former Sanford ally. “The law is the law and when a judge says you shouldn’t be at Jenny’s house, you should probably listen. It feeds the story line that he sees himself above the law.”

Cash-flush outside groups have no plans to help him either. A spokesman for the Club for Growth said that they had no plans to support Sanford, whose fiscal conservatism is in line with the group’s philosophy.

“We have not been involved in the race in South Carolina’s 1st Congressional District, in the primary, in the runoff or in the general,” said Barney Keller, a spokesman for the club. “We don’t expect that to change.”

No other outside GOP groups have made advertisement reservations to help Sanford either, a GOP source noted.

In recent cycles, it has become increasingly common for third-party groups and super PACs to make big advertisement buys in special elections. Last cycle, third-party groups made massive advertisement buys in special elections when the party could not afford to go on the airwaves.

Even in this special election for the coastal 1st District, House Majority PAC has already started airing spots on behalf of Colbert Busch. However, the Democratic Congressional Campaign Committee has not made any such investment yet.

The NRCC's decision means Sanford is alone. Republicans quickly compared the trespassing report to the Sanford’s infamous international trip that made national headlines.

In 2009, when he was governor, Sanford told his staff he went on a hike on the Appalachian Trail. However, he was in Argentina engaged in an extramarital affair.

Earlier on Wednesday, Sanford aimed to subtly put the blame on his ex-wife, Jenny Sanford. In a statement, Sanford noted he was “particularly curious how records that were sealed to avoid [his sons’] embarrassment” became public.

But Republicans don’t care how the records became public. They say it would have been political malpractice if Democrats had not found the casework themselves.

Most importantly, national Republicans argue that if they had known about the report, they could have contained the damage.

“People will drill down and try and determine where it came from,” said one senior GOP Hill staffer. “It doesn’t matter. It didn’t come from Mark Sanford and it should have.”

Regardless of whether Sanford wins this contest, Republicans are already looking to 2014. They compare Colbert Bush to the short-lived congressional career of former Rep. Bob Turner, a New York Republican who won a solidly Democratic district in a 2011 special election.

The special election’s victor will succeed Tim Scott, a Republican appointed to the Senate earlier this year.